Connection of a Logitech Z5450 to Pace 1000

[boxcar]

Help needed here pls. I have just received a Logitech Z5450 Home Theatre Speaker system and I need to hook this up with my [old] Pace 1000 stb. Hooking up my DVD player was easy, a digital optical link was all that was needed. Now comes the hard part! VM tell me that the output from the 'audio left' and 'audio right' on the back of my stb are digital, since NTL upgraded to digital. On the back of the Control Centre of the Z5450 there is a digital coax connection [input]. Can anyone 'advise' me that if I were to use a 2xphono plug-to-1xphono plug cable [ie - a splitter type], would I get an audio link between the stb and the CC of the Z5450? This is all a bit new to me, so would welcome any help anyone 'viewing' can give me.